These are differential transducers contained in a watertight housing. The reference port is vented to atmosphere via the power supply and signal cable, while the measuring port of the transducer is connected to a copper outlet nozzle on the top of the transducer housing.
The copper nozzle, transducer measuring port and connecting tube are filled with oil so the pressure is transmitted to the crystal element via the oil, thus keeping the transducer components free from the effects of the saltwater.
Measurement devices
Tide gauge systems
Tide gauges
Instruments